What Would Cause Sudden Rich Condition?

mca · 12-24-2010, 09:49 AM

Here is the story ... I added a H4 relay kit and new H4 assemblies. Car has only been sitting for a week and a half. Doubt the H4 install is related but seems like odd coincidence.

I wrapped up the work and took her for a spin. Fired up like normal - high idle (seemed unusually high this time) then settled down. But didn't settle all the way down like usual. Hung at about 1200rpm

After reaching operating temps I experience a HUGE surge at idle. It would almost cut off and then immediately jump up past 1000rpm. The typical symptom of an overly rich condition.

My initial guess is that the AAR isn't closing all of the way.

Thoughts?

Joe Bob · Joe Bob's Garage

Intake leak somewhere.....that's the first suspect on CIS when the idle goes high and/or hunts.

mca · 10:21 AM

Wouldn't that make it lean? A la removing the oil cap?

All intake hoses, injectors, and seals are new since 10k miles ago.

I can certainly smell the richness.

The AAR is closing all of the way. So that is ruled out.

Gogar · 12-24-2010, 10:23 AM

No 12V at the WUR and/or the AAR?

equality72521 · 12-24-2010, 10:25 AM

Quote:

Originally Posted by Gogar

No 12V at the WUR

That is exactly what happened to mine. I temporarily swapped the Amp plugs from the AAR to the WUR and bingo.

mca · 12-24-2010, 10:52 AM

Quote:

Originally Posted by Gogar

No 12V at the WUR and/or the AAR?

Can you explain how I test this? I'm not the best at reading / interpreting electrical diagrams and performing tests. Never been shown how.

I'm guessing that I unplug the wur, turn the ignition to the "on" position, touch the positive lead from the voltmeter to one of the contacts on the unplugged plug - ground the negative lead from the voltmeter to the somewhere on the engine.

Could any of this be a result of the mods I made with the H4 relay kit?

boyt911sc · boyt911sc's Garage

Quote:

Originally Posted by equality72521

That is exactly what happened to mine. I temporarily swapped the Amp plugs from the AAR to the WUR and bingo.

Mark,

How did you do it? You purposely switched the AAR's plug to WUR and vice versa? Or it was by accident? I can't imagine how you could plug them reversely with the CIS installed. What were you trying to achieve by switching the plugs? Just trying follow your statement. Thanks.

Tony

equality72521 · 12-24-2010, 11:04 AM

Quote:

Originally Posted by boyt911sc

Mark,

How did you do it? You purposely switched the AAR's plug to WUR and vice versa? Or it was by accident? I can't imagine how you could plug them reversely with the CIS installed. What were you trying to achieve by switching the plugs? Just trying follow your statement. Thanks.

Tony

I did it on purpose. I lost 12v at the WUR plug but still had 12v at the AAR plug. Somewhere in the harness the wire feeding the WUR failed open while I was on the road. I checked each out and found I still had 12v at the AAR so I unplugged it and plugged it into the WUR until I could get home and fix it. I could live without a working AAR.

Gogar · 12-24-2010, 11:11 AM

Quote:

Originally Posted by mca

Can you explain how I test this? I'm not the best at reading / interpreting electrical diagrams and performing tests. Never been shown how.

I'm guessing that I unplug the wur, turn the ignition to the "on" position, touch the positive lead from the voltmeter to one of the contacts on the unplugged plug - ground the negative lead from the voltmeter to the somewhere on the engine..

Sort of. Go to the fuse box and pull the fuel pump relay, which is the red one closest to the windshield. You need a little piece of wire to 'jump' the pins 30 and 87a. 30 is the one that's all by itself, and 87a is 2 pins clockwise from 30. You can look on the base of the relay you just removed to make sure. Stick the wire in the sockets to 'jump' those two connections.

(if you're uncomfortable doing this, you can also just remove the air cleaner and push the sensor plate and accomplish the same thing, but you'll need more arms to do it.)

Find the WUR (it's bolted to intake runner #2, and probably behind some heater pipes.) There's a square electrical plug you should be able to remove. Stick your meter on there (brown wire is ground, the other is +)

Turn on the ignition. Don't start the car.

With that fuel pump relay jumper in place, check for 12V. at the WUR connection.

jjwood · jjwood's Garage

Winng the lottery comes to mind. sorry couldn't resist... it's CHRISTMAS!

mca · 12-24-2010, 11:23 AM

Quote:

Originally Posted by Gogar

Sort of. Go to the fuse box and pull the fuel pump relay, which is the red one closest to the windshield. You need a little piece of wire to 'jump' the pins 30 and 87a. 30 is the one that's all by itself, and 87a is 2 pins clockwise from 30. You can look on the base of the relay you just removed to make sure. Stick the wire in the sockets to 'jump' those two connections.

(if you're uncomfortable doing this, you can also just remove the air cleaner and push the sensor plate and accomplish the same thing, but you'll need more arms to do it.)

Find the WUR (it's bolted to intake runner #2, and probably behind some heater pipes.) There's a square electrical plug you should be able to remove. Stick your meter on there (brown wire is ground, the other is +)

Turn on the ignition. Don't start the car.

With that fuel pump relay jumper in place, check for 12V. at the WUR connection.

Thanks. I've already got an inline fuse jumper set up for the fuel pump relay. Did a bunch of pressure tests in the past.

Can't I just perform this test with the car running or is that too risky?

The only other thing I did today was cut out my crumbled O2 sensor connector in the engine bay - just wrapped the wire with electrical tape. Been running without the sensor for years because of the faulty connector. I was planning on installing my new connector today but ran out of time. Regardless, the car runs perfectly well - set CO at 2.5% for now.

Gogar · 12-24-2010, 11:48 AM

Oh sorry I was just trying to be over-descriptive.

Yes I suppose you could do it with the car running.

boyt911sc · boyt911sc's Garage

Craig,

Since you are familiar with the FP test (jumpering 87a-30), this is a good way to check the electrical outputs of the other CIS components. FP, AAR, AAV, & TV (optional) all gets power from #30. In summary, all the stuff connected to terminal #30 get power when energized.

Secondly, I try to stay away from using the AFS while troubleshooting for power (12 volts). Plus you don't need to dump unnecessary fuel into the manifolds that could contribute additional problem.

Are you sure the fuel control pressure is within spec (cold condition)? Just a thought. Keep us posted.

Tony

mca · 12-24-2010, 12:21 PM

Quote:

Originally Posted by Gogar

Oh sorry I was just trying to be over-descriptive.

I appreciate that - exactly what I wanted and needed to know.

mca · 12-24-2010, 12:24 PM

Quote:

Originally Posted by boyt911sc

Craig,

Since you are familiar with the FP test (jumpering 87a-30), this is a good way to check the electrical outputs of the other CIS components. FP, AAR, AAV, & TV (optional) all gets power from #30. In summary, all the stuff connected to terminal #30 get power when energized.

Secondly, I try to stay away from using the AFS while troubleshooting for power (12 volts). Plus you don't need to dump unnecessary fuel into the manifolds that could contribute additional problem.

Are you sure the fuel control pressure is within spec (cold condition)? Just a thought. Keep us posted.

Tony

Thanks Tony. I'll do that.

However, my first step is going to be to take the new H4 relay kit out of the equation. I have a lot of confidence in this car and find it hard to believe that I would suddenly have this condition immediately after installing the H4s. My guess is that they are somehow putting a strain on the system. We shall see.

I'll get on that tomorrow morning and post results.

Joe Bob · Joe Bob's Garage

Funny thing, I was installing a relay kit for my Cibies and had a switched power failure to my DME.....relays are evil.

It's a real pisser when ya reach for the key after an upgrade and you get nada.....kinda like Microlimp upgrades on my laptop. 1 outta 3 gives me the 20 minute reboot with an occasional bluescreen of death.....

boyt911sc · boyt911sc's Garage

Craig,

What fuse # did you hook up the H4 relay? Did you use S18 by chance for the connection? I doubt the relay has something to do with the problem but who knows!!!! Keep us posted.

Tony

mca · 12-24-2010, 01:44 PM

I tied into 6 and 8 in the fuse panel - high beams / low beams. The lights work fine and signals still work. Who knows.

don gilbert · don gilbert's Garage

once the car warms up, you dont really need 12v at wur, it takes very little heat for it to bend the spring. I dont think power is the prob. although it would just take a min. to check with a 12v test lite. I think tony is on the rite track with control press. not rising to spec. The wur gets finicky sometimes, esp. during extreme weather changes. I would throw on the gages just to check i you think the mix is to rich suddenly.

mca · 12-25-2010, 06:21 AM

I disconnected the H4s and went for a drive. After 30 minutes (at least) of driving up and down the same street ... starting and stopping ... I was convinced that the idle surging was due to the new H4 relays because the surge was gone. On my last turn around before heading home the idle surge returned.

I turned the car off and decided to pull the decel valve vacuum line. Cranked her back up and all was well. After 20 minutes of further testing I found no more idle surge. In order to verify that the decel valve was the culprit, I reconnected the vacuum line. Idle immediately began to surge up and down in major fashion.

A couple of years ago I did the decel valve squish (specified in a technical bulletin). I guess it finally gave up the ghost.

Unless the decel valve magnifies a problem elsewhere in the system, I'm going to chalk it up to decel valve failure.